Thawing a completely frozen ham takes around 6 hours but sometimes can take as long as 24 hours depending on the size of the ham.
A good way to thaw out a ham is to put the ham in a leak proof bag and submerge the ham in cool water for 30 minutes and after 30 minutes remove the ham and replace the water with fresh water again and submerge the ham for another 30 minutes.
Then you might have to continue thawing it out in the refrigerator overnight the night before you plan to cook the ham.
That's what I do is I make sure to thaw the ham out the night before the next day I'm gonna cook it to allow time to thaw.
You might also be able to thaw the ham out in the microwave by putting the microwave on defrost and it should thaw within an hour or 2 that way.
But I've never tried that and just thaw it out in water and the refrigerator which has always worked for me.